Energy systems with high shares of renewable electricity are feasible, but require balancing measures such as storage, grid exchange or demand-side management to maintain system stability. The demand for these balancing options cannot be assessed separately since they influence each other. Therefore, a model was developed to analyze these mutual dependencies by optimizing a concerted use of balancing technologies. This model is presented here. It covers the European electricity system in hourly resolution. Since this leads to a large optimization problem, several options for reducing system complexity are presented. The application of the model is illustrated with a case study outlining the effects of pumped hydro storage and controlled charging of electric vehicles in central Europe.